The present invention relates generally to material handling systems and, more particularly, to controlling a vacuum generator for suction cups of material handling systems that are engaged with the objects and substantially sealed thereto via operation of the vacuum system comprising the vacuum generator and the suction cups. It is known to provide a material handling system that includes suction cups or the like that are adapted to be moved into engagement with an object, such as a substantially flat object or panel or the like, and to lift and move the object to a desired location. The suction cups may be moved into engagement with the object, and the vacuum generator may be actuated to create a vacuum between the object and a suction cup such that the object is retained to the suction cup as it is transported to the desired location.
The vacuum generated at the suction cup(s) is provided by the vacuum generator in the vacuum system, whereby pressurized air is supplied or provided to the vacuum generator.
When the air supply to the vacuum generator is deactivated, such that no vacuum is generated, the vacuum in the vacuum system may dissipate through a vent that connects the vacuum system to an atmosphere outside of the system, and when the vacuum has dissipated in the system and in the cup, to a sufficient amount, the suction cup may be released from the object.
Prior art devices are known from e.g. EP-1064464 where it is disclosed a vacuum ejector pump for generating a negative pressure used for transportation or lifting purposes. And in, U.S. Pat. No. 7,950,422 where it is disclosed an auto-release vacuum device for a material handling system.
Although presently used vacuum systems for transportation have many advantages, the time to vent the system and/or the vacuum cup(s), is in some occasions considered too long.
The object of the present invention is to achieve an improved vacuum system that eliminates, or at least mitigates, the above stated drawbacks, by being more user-friendly to handle, and having shorter deactivation times.
It is known, in order to reduce cycle times in industrial production lines, to provide vacuum generators having arrangements for the active release of objects from the suction cup(s). A known solution is to vent, typically to connect the suction cup(s) or the supply line with atmospheric pressure, for instance via a controlled valve.
Prior art devices are known from e.g. EP-B1-2263011 where it is disclosed a vacuum generator, driven by high-pressure air, and having means arranged for active release of an object that is gripped in a suction cup.
Although presently used systems have many advantages the used devices, the time to vent the suction cup(s), is in some occasions considered too long. There is also a problem that sometimes suction cups stick to a surface because the vacuum system does not allow for atmosphere to enter the system, at least not fast enough.
An object of the present invention is to provide a method, control unit and vacuum system for controlling a vacuum ejector device that eliminates, or at least mitigates, the above stated drawbacks.